Process of preparing solutions of gases.



PROCESS OF PREPARING SOLUTIONS OF GASES. AIPLIOATION FILED APR.17. 1906.

I I I L 712 671655 6-5 I EZCGILZIO 2" UNITED STATES PATENT OFFICEc HENRY HOWARD, OF NORTH WOBURN, MASSACHUSETTS.- PROCESS OF PREPARING'SOLUTIONS OF GASES.

Specification of Letters Patent.

Patented Nov. 20, 1906.

To alll whom it may concern: Be it known that I, HENRY HOWARD, a

- citizen of the United States, residing at North Woburn, in the State of Massachusetts, have invented certain new and useful Improvements in Methods of Pre aring Solutlons of Gases, of which the fol owing is a specification.

This invention is a method of preparing solutions of gases. of any desired concentration.

The'invention will be described as applied to the preparation of sulfite liquors containing free sulfur dioxid, but is not restricted thereto.

In the use of sulfite solutions for the production of cellulose it is essential for the most effective and economical working that the solution should contain'a certain proportion of uncombined sulfur dioxid and that this proportion should be within the control of the o erator. When such liquors are produced y subjecting a solution containing lime or other base to contact with sulfur dioxid produced by burning sulfur or py'rites in air, and more particularly in the latter case by reason of the greater dilution of the sulfur dioxid, it often occurs that the percentage of free sulfur dioxid is less than is desirable or necessary. According to my invention such percentage is increased to any desired extent up to the amount corresponding to the saturation-point of a solution of given temperature under an atmosphere of pure sulfur dioxid at a given pressure' I accomplish this result by bringing the dilute sulfur dioxid produced by thev combustion ofsulfur or of py'rites into contact with a solvent liquor and a sorbing it therein. I then expel the absorbed gas from such liquor or a portion thereof, and after separating art or all of the moisture from the gas, if t is should be deemed desirable, I cause the 'gas to' be 'absorbed to the desired extent in the sulfite liquor. Preferably I prefer a sulfite solution containing'free sulfur dioxid by means of burnergases in the usual way and subsequently expel the gas from a portion of said solution and absorb it in another portion thereof, thereby increasing the gas content of the second-mentioned portion to any desired extent. The portion of the li nor from which the gas has been expelled is t en brought into I,

' ing, wherein theifi contact with the burner-gases for restoring its content of sulfur dioxid. The method is readily made continuous, and any desired sulfur-dioxid content is secured 'by properly pro ortioning the portion of the liquor from WlJlOll the gas is expelled to that in which the expelled gas is reabsorbed. Preferably, also, I effect an interchange of heat between the expelled gas and the inflowing solution and between the heated liquor and the'inflowing solution, whereby a considerable economy is effected.

' For a full understanding, of my invention reference is made to the accompanying drawe is an elevation, partly in section, of one orm of apparatus for carrying my method into effect.

1 1s a storage-tank for sulfite li uors prepared from burner-gases in the usua manner. 2 3 are saturation-tanks wherein the sulfurdioxid content of this liquor may be increased, and 4 is a storage-tank for the resulting sulfite solution. Solution flows from tank 1 through pipe 5, having a cock 6, to the saturator ,2, overflows therefrom through 7 to the saturator 3, and passes thence ipe iiy pipe 8 to the storagetank 4. Solution from tank 1 is also permitted to flow through pipe -10, provided with a cook 11, to a boiler or sulfur-dioxid generator 9, traversing in its passage two heaters or heat interchanges 12 and 13, each of which is shown as comprising a' coil within a'closed tank, the solution from tank 1 passing around the coil in heater 12 and through the coil in heater 13. From heater 13 the solution passes by pipe 14 to the generator 9. This generator may be of any suitable construction. As shown, it com rises a relatively shallow closed tank sub ivided into several compartments by partitions 15 16 so arranged as to afiord a restricted communication between adjacent compartments, liquid being introduced at one end of the tank through pipe 14, traversing the several compartments in succession and escaping at the opposite end through pips 17.

ive steam is blown into the generator 1 through pipe 18, having inlets to the several com artments, and serves to expel the sulfur dioxld from the solution therein. The expelled gas, together with the steam, is conducted through pipes 19 to the coil in heater I lution from tank 1.

' pipe 22, preferably traversing the heater 13,

as shown. The substantially pure sulfur d'ioxid is conducted from the trap 21 by ipe 23 to the saturator 3, wherein it is who y or in part absorbed by liquor from tank 1, any unabsorbed portion passing by ipe 24 to saturator 2, thence by pi e 25 to be added to the burner-gases and ut1 ized in the preparation of solution for tank 1. The heated solution from which sulfur dioxid has been expelled in the generator 9 overflows therefrom through pipe 17 into heater 13. Thence-it flows by pipe 26'to a cooler27, inwhich it is fully cooled by water, passing then through pipe 28 to the usual absorbing system, wherein it is brought into'contact with the burner-gases and utilized in the preparation of solution for tank 1. It is understood that lime and water are added at the regular absorbing system in the usual way.

It will be'ob'served that the volume and suliur-dioxid content of the rep-ared solution passing to the storage-tan 4 is absolutely controlled by manipulation of cocks 6 and 11, the concentration of this solution with I respect to sulfur dioxid being increased or diminished b pro rti'ono to t e generator 9.

In practice cocks 6 and 11 are somanipulated as to insure at all times the reparation of solution which shall correspond in volume plermitting a greateror smaller 17 and in the percentage of absorbed'gas to the requirements of the digesters. claim 1. The method of preparing solutions of gases which consists in partially saturating a liquid with gas, then ex elling the gas from one portion of the liqui and absorbing it in another portion thereof, and subjecting the rtion of the liquid from which the gas has een expelled to contact with additional gas to again partially saturate it; substantially as described. I

2. lhe method ofpreparing solutions of ases which consists in partially saturating a iqluid by contact with diluted gas, then expe ling the gas from one and absorbing it in anot er portion thereof, and subjecting the ortion of the liquid from which the gas has een expelled to contact with additional gas to agam partially saturate it; substantially as described.

3. The method of preparingsolutions of ases which consists in partially saturating a- %quid with gas, then expelling the gas from expe led gas by transferring heat there om e liquor from tank I to pass .stantially as described.

ortion of the liquid season one ortion of the liquid and absorbing it in 6 anot er portion thereof, subjecting the portion of. the liquid from which the gas has been expelled to contact with additional gas to again partiall saturate it, and re eating the operatlon; su stantially as descri ed.

ases which" consists in partially saturating a iquid with gas, then expplling the gas from one ortion of the liquid y heat, coolin the to further portions of said liquid and absorbing the gas in a portion of the original liquid and thereby increasingthe gas content of said liquid to the extentdesired; substantially as described.

5. Themethod of preparing solutionso ases which consists in partially saturating a iquid with gas, then expelling the gas from one ortion of the liquid by heat, coolin the expe led gas by transferrin heat there cm to further portions of said iquid, absorbin the gas in a portion of the original liquid and thereby increasin' the gas content of said liquid to the desire extent, and sub'ecting the ortion of the liquidfrom which -t e gas has been expelled to contact with additional gps to, again partially saturate it, substanti as described.

6. The method of treating which consists in expelling sulfur dioxid from a rtion of such liquor, absorbing the ex- 'pe led gas in another portion thereof, and

subjecting the portion of the liquid from which the gas has been expelled to contact with additional sulfur dioxid to restore its content thereof; substantially as described.

7. The method of treatin sulfite liquor which consists in ex elling sul a ortion of such hquor, absorbing. the ex-'. pe led gas inanother ortion thereof, subthe {gas has been expelled to contact with thereof, and repeating the operation; sub-.

8. The method which consists in preparing a sulfite liquor containing an excess of sulfur dioxid, expelling sulfur dioxid horn a portion of said liquor by heat, cooling the expelled sulfur dioxid by imparting heat therefrom to; further portions of said li uo'r, absorbin the sulhir dioxid in a portion 0 the original 11 upr and thereby increasing its content of su fur dioxicl to the degree desired, and subjecting the orti-on'of the liquorffrom which the gas has en ex elled to contact with additional .suliur diom' to restore, its content thereof,

substantially as described. n Y

9. -'lhemethod of-preparing sulfiteliquor, which consists in bringing di uted sulfur dioxid into presence of a suitable solvent and thereby formin a solution containing gas, then expelling t e gas from said solution and r 1 4. The method of preparing solutions of ff sulfite liquor I fur dioxid from i 10" ecting the portion of t e liquid from which) I It absorbing the relatively concentrated gas in ing the relatively concentrated gas in a sula sulfito solution; substantially as described. fite solution, substantiall as described. [0 10. The method of preparing sulfite liquor, In testimony whereof l afl ix my signature which consists in bringing diluted sulfur diin presence of two witnesses.

oXid into presence of a suitable solvent and HENRY HOWARD. thereby forming a solution containing the Witnesses:

gas, then expelling the gas from said solution, WARD B. KEITH,

separating moisture therefrom, and absorb- EDWIN R. BOND. 

